微细切削毛刺的有限元仿真

在微细加工精密微小零件的过程中,存在的主要问题之一是有微型毛刺产生。利用有限元软件Abaqus对铝2024-T3微细切削进行仿真,运用Johnson-Cook(J-C)模型建立工件材料模型,用网格自适应技术(arbitrary Lagrangian Eulerian,ALE)实现切屑和工件的分离,切屑和刀具的接触摩擦模型采用修正的库仑摩擦定律,动态模拟微型毛刺的形成过程,分析不同刀具几何参数及切削参数对毛刺形成的影响,得到微细加工过程中不同刀具几何参数及切削参数对微型毛刺形成影响的一般规律。分析结果为优化刀具几何参数及切削参数、减少微细切削中的毛刺和提高表面加工质量等提供指导。     

Ti-6Al-4V车削温度的有限元仿真研究

分别采用有限元分析软件AdvantEdge FEM和DEFORM-3D,选取相同的模拟参数,对钛合金Ti-6Al-4V的车削加工过程进行了三维有限元仿真,根据仿真结果,分析总结出切削热的整体分布情况和刀具、切屑及工件切削温度的分布规律,给出了不同车削速度下刀具前后刀面温度分布图,模拟分析了同一切削速度不同分析步和不同切削速度下的刀具、切屑及工件的温度场分布情况,并把两个软件的仿真结果进行对比分析,得出了分析结果,为深入研究切削机理提供了有益的参考数据.     

麻花钻钻削过程的有限元动态仿真

孔钻削加工是一种常见且非常重要的金属加工工艺,麻花钻是钻孔加工中最普通的加工工具,文章用有限元方法模拟了麻花钻的钻孔加工过程进而分析预测了加工工艺中的部分结果和影响因素。应用的有限元仿真软件是DEFORM-3D。论文中动态模拟了麻花钻钻孔中切屑成形过程,工件采用了刚塑性材料模型,而刀具采用的是考虑温度变化的刚性材料模型,获得了麻花钻钻削加工过程中的连续切屑,分析预测了加工过程中工件的应力、温度分布以及刀具所受的扭矩。     

基于ABAQUS的金属切削数值模拟分析

采用ABAQUS有限元软件对切削过程进行了2D和3D数值模拟,分析了切削深度、切削速度等切削工艺参数和刀具前角、刃倾角等刀具几何参数对切削过程的影响;分析过程中考虑切削产生的热量对切削变形的影响,获得了切削应力场、应变场以及温度分布;通过观察和分析切削后表面粗糙度和切屑形状等,为刀具设计和确定工艺参数提供依据。     

基于有限元模拟的高速切削中切削热的研究

基于有限元分析软件DEFORM-2D建立了典型的正交切削模型,模拟分析后得到切屑厚度、刀—屑接触长度和X、Y方向切削分力等参数值;结合剪切面及前刀面接触区的平均温度和切削热解析法,研究了高速切削中切削热在切屑、工件和刀具部分的量化分配规律。     

基于DDFORM-3D的高速车削有限元模拟

基于有限元分析软件DEFORM-3D建立高速切削的切削力预报模型，并对车削力和工件、刀具及切屑的温度分布进行模拟。该模拟结果对实际工作有现实的作用。     

金属正交切削工艺的有限元模拟

切削加工是一种重要的金属制造工艺 ,其中切屑成形是一种典型的大变形问题 ,它涉及到材料非线性、几何非线性以及边界非线性问题 ,在高速切削加工过程中 ,还会涉及到热力耦合问题。本文针对典型的正交切削工艺 ,建立了平面应变模型 ,工件采用了弹塑性材料模型 ,而刀具采用的是考虑温度变化的刚性材料模型。利用商业化软件DEFORM-2 D,对所建立的模型进行了有限元分析 ,得到了切屑成形、温度分布、切削力变化以及残余应力等结果。将部分结果与文献中介绍的实验结果做了比较 ,发现他们是吻合的     

基于有限元法的二维正交切削刀具应力分析

运用有限元方法对二维正交切削加工刀具内部应力进行模拟分析。基于刚塑性有限元方法建立了切削加工过程仿真模型,通过模拟获得了切削加工过程中刀具应力的分布和变化情况。通过对不同切削工艺参数条件下的切削过程进行模拟,分析了刀具几何参数以及切削用量对切削加工过程中刀具应力的影响,为正确选择刀具及切削参数提供了参考。     

虚拟制造技术在切削加工中的应用

利用虚拟制造技术对金属的切削加工过程进行了模拟仿真研究。按照实际加工条件建立了切削模拟模型 ,按照国家标准建立的硬质合金可转位刀片的三维模型既考虑到真实的刀片几何形状 ,也考虑了其安装角度参数。利用软件DEFORM3D对金属切削过程中的切屑流动状态及过程中的温度场和应力场进行了模拟加工并分析了模拟结果。     

钻削高强度钢的切屑形态仿真及试验研究

为探究钻削34CrNi3MoV高强度钢时切屑形态的变化规律,一方面,通过运用AdvantEdge有限元仿真软件,通过选取不同的刀具几何参数和切削用量的组合,进行钻削加工过程的仿真,得到不同切削条件下的切屑几何参数及切屑形态;另一方面,在加工中心上进行钻削34CrNi3MoV高强度钢的切削试验,通过试验与仿真结果的对比分析,进一步验证切屑形态仿真结果并分析其原因。研究结果表明,钻削加工高强度钢时,通过改变刀具几何参数和切削用量可以有效地改变切屑形态及切屑几何参数,为实现高效钻削高强度钢的实际应用提供理论基础。     

Finite element modeling of 3D turning of titanium

The finite element modeling and experimental validation of 3D turning of grade two commercially pure titanium are presented. The Third Wave AdvantEdge machining simulation software is applied for the finite element modeling. Machining experiments are conducted. The measured cutting forces and chip thickness are compared to finite element modeling results with good agreement. The effects of cutting speed, a limiting factor for productivity in titanium machining, depth of cut, and tool cutting edge radius on the peak tool temperature are investigated. This study explores the use of 3D finite element modeling to study the chip curl. Reasonable agreement is observed under turning with small depth of cut. The chip segmentation with shear band formation during the Ti machining process is investigated. The spacing between shear bands in the Ti chip is comparable with experimental measurements. Results of this research help to guide the design of new cutting tool materials and coatings and the studies of chip formation to further advance the productivity of titanium machining.     

A MACHINING PERFORMANCE STUDY IN DRY CONTOUR TURNING OF ALUMINUM ALLOYS WITH FLAT-FACED AND GROOVED DIAMOND TOOLS

This paper presents the results from an experimental study of dry contour turning operations on aluminum alloys (6061B and 2011-T3) using PCD flat-faced and diamond coated grooved tools. The machining performance is assessed on the basis of cutting forces, chip flow, chip-form and surface roughness observed during contour turning operations. The constantly varying cutting conditions (especially effective depth of cut due to varying geometry of the contour surface) and effective tool geometry cause a wide fluctuation in cutting forces and the ensuing chip flow. The chip flow angle is measured along the contour geometry using high-speed filming techniques and these results are compared with predicted chip flow values from the measured experimental cutting forces (which are measured along the entire contour geometry). The resultant surface roughness at different locations along the contour profile is measured and correlated with the chip flow and chip-form variations. Machining performance issues specifically relevant to dry contour turning of aluminum (such as problems due to poor chip flow and the resultant poor surface roughness) are studied and the effectiveness of selective work-tool (both tool material and tool geometry) pairs is illustrated.     

Investigation and prediction of chip geometry in diamond turning

Management of the chips generated in diamond turning is often critical, because contact between chips and the workpiece can result in superficial damage to the finished surface. Controlling chip motion is not a trivial process as the proper positioning of an oil or air stream requires an understanding of the dynamics of a diamond turned chip and the machining parameters that affect it. Work has been performed to investigate the effects of cutting speed, depth of cut, tool geometry, tool wear, and workpiece material properties on chip motion and geometry. Utilizing radius of curvature data from cutting experiments, a parameter has been proposed that can be used to predict chip radius of curvature for a wide range of machining conditions. This chip curvature parameter, χ, exhibits a power law relationship with chip radius of curvature as a function of tool geometry, depth of cut, cutting speed, and both elastic and plastic properties of the workpiece material.     

FORCES AND TEMPERATURES IN HARD TURNING

In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer).     

FORCES AND TEMPERATURES IN HARD TURNING

In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer).     

Realistic simulation of surface defects in five-axis milling using the measured geometry of the tool

Managing macro- and micro-geometry of surfaces during manufacturing processes is a key factor for their following uses. Indeed, micro-geometry and surface topography are directly linked to the performances of functions (contact, friction, lubrication, etc.) by texture parameters to ensure the desired local geometry. Common models for simulation of surface topography are based on ideal geometry of the machining tool and cannot represent surface defects. The actual prediction and simulation of defects are one step forward in a competitive context. In this paper, the realistic model proposed aims to simulate and predict as finely as possible local defects of machined surfaces taking into account the actual edge geometry of the cutting tool. The combined use of the machining kinematics and of the measured geometry of the cutting edges leads to the representation of the geometrical envelope of the surface using a Zbuffer technique. Simulation assessment is carried out by the analysis of 3D surface topography parameters such as surface complexity and relative area and by a comparison of simulation results to an experimental case of study.     

高速铣削淬硬钢时切削载荷平稳化研究

和传统的铣削加工相比,高速铣削淬硬钢更需要稳定的切削载荷,以尽可能减少刀具碎裂和过度磨损。本研究借助三向压电石英测力仪,使用TiAlN涂层球形端铣刀,在13500 r/min的转速下,对淬火45#钢(47HRC~48HRC)进行了高速铣削试验,建立了高速铣削下的多项式切削力试验模型,模拟了以恒定切削力为目标、优化进给率的加工实例。结果显示,稳定的切削载荷能有效地提高加工效率,避免刀具剧烈磨损。     

Investigation of the direction of chip motion in diamond turning

Management of the chips generated in diamond turning is often critical since contact between chips and the workpiece can result in superficial damage to the finished surface. Controlling chip motion is not a trivial process as the proper positioning of an oil or an air stream requires an understanding of the dynamics of a diamond turned chip and the machining parameters that affect it. Previous work [1] introduced the chip curvature parameter, χ, which is useful in predicting chip radius of curvature over a wide range of cutting speeds, depths of cut, tool geometries and workpiece material properties. To control chip motion, however, an understanding of the direction chips leave the tool/workpiece interface must also be obtained. Cutting experiments were performed investigating the influence of cutting speed, depth of cut, feed rate, tool path angle, tool geometry and tool orientation on the directional characteristics of the motion of diamond turned chips. Flow angle measurements obtained during cutting were found to remain within ± 10° of predictions from a simple geometrical model originally proposed for conventional machining.     

Tool wear and chip analysis after the hard turning of AISI D6 steel assisted by LN2

Abstract

Sustainability is a concept which is widely considered nowadays, including in factories where machining operations are present. The search for methods able to improve the performance of industrial processes without damaging the environment or the worker’s health has been the main goal of several investigations. In this context, cryogenic machining is a technique that has been studied as an alternative to the use of mineral oil-based cutting fluids, mainly in the machining of titanium and nickel alloys. Investigations on the cryogenic machining of hard tool steels are still scarce in the literature. This article presents results from a series of turning trials under dry and cryogenic conditions using a hardened AISI D6 tool steel bar (57 HRC) as the workpiece. For the cryogenic machining tests, liquid nitrogen was delivered to the flank face, rake face and on both faces of PCBN inserts. The main cutting parameters (cutting speed, feed rate, and depth of cut) were kept constant during the trials. Tool wear and chip morphology were the output variables studied. The results show that the liquid nitrogen was able to reduce the cutting tool wear, providing a tool lifetime around 50% longer compared with the dry process. Moreover, the frequency of chip segmentation was diminished under cryogenic conditions in comparison with the dry process.